Cartilage and chondrosarcoma contain growth factors capable of stimulating DNA synthesis and cell division in cultured cells. The cartilage-derived growth factor (CDGF) has been purified to homogeneity and is a polypeptide of molecular weight 16,300 plus 200 or minus with an isoelectric point between 9 and 10. CDGF is synthesized by chondrocytes and is apparently a chromosomal protein. When chondrocytes are subfractionated into cytoplasts and karyoplasts, all of the growth factor activity is found in the karyoplasts. Furthermore, all of the growth factor activity in the karyoplast is found to be associated with chromatin. CDGF stimulates the proliferation in vitro of several cell types that are involved in bone formation. These cells include chondrocytes, osteoblasts and capillary endothelial cells. CDGF also stimulates the migration of capillary endothelial cells in vitro. Our goals are to elucidate the mechanism of action of CDGF, to find out which cells are targets for CDGF in vivo and to compare the growth factor activity of normal cartilage and chondrosarcoma. The direct objectives of the proposed research are: 1) to continue purification and characterization of CDGF, 2) to purify the chondrosarcoma-derived growth factor, 3) to investigate the mechanism of action of CDGF, 4) to investigate the role of CDGF as a stimulator of capillary endothelial cell proliferation and migration in vitro and of capillary proliferation and migration in vivo, 5) to raise antibodies against CDGF, and 6) to use CDGF to enhance the growth rate of cells in culture, particularly primary amniotic fluid cells obtained in amniocentesis.